Elastomer-modified epoxy siloxane compositions

ABSTRACT

Elastomer-modified Epoxy-polysiloxane compositions of this invention are prepared by combining a silicone intermediate, with an epoxy resin, an elastomeric resinous intermediate, a polyfunctional amine, an optional organometallic catalyst, and optional fillers, pigments, and processing agents. The composition is prepared using a sufficient amount of water to promote hydrolysis of the polysiloxane and the polycondensation of the silanols produced by such hydrolysis. In its cured form, the epoxy-polysiloxane composition exists as a uniformly dispersed arrangement of linear epoxy chain fragments that are cross-linked with a continuous polysiloxane polymer chain, wherein either or both of the epoxy and/or polysiloxane polymers are elastomer modified to provide coatings and floorings having significantly improved properties of impact resistance, flexibility, crack resistance, and abrasion resistance with compared to conventional epoxy systems.

RELATION TO COPENDING PATENT APPLICATION

This patent application is a continuation of U.S. patent applicantionSer. No. 10/062,243 that was filed on Feb. 1, 2002, and that issued onOct. 28, 2003 as U.S. Pat. No. 6,639,025.

FIELD OF THE INVENTION

This invention relates to epoxy resin based compositions useful forprotective coatings and the like and, more specifically, toelastomer-modified epoxy siloxane polymer compositions having improvedproperties of flexibility, weatherability, and chemical resistance.

BACKGROUND OF THE INVENTION

Epoxy siloxane compositions useful for application as coating materialsare well known, and have gained commercial acceptance as protective anddecorative coatings for steel, aluminum, galvanizing, wood and concretein maintenance, marine, construction, architectural, aircraft andproduct finishing markets. While epoxy-based compositions have long beenknown for their desired properties of good adherence to substrates,corrosion resistance, and chemical resistance, and weatherability, theyhave suffered from less than ideal properties of weatherability andrelated gloss retention. Epoxy siloxane compositions were developed toprovide improved properties of weatherability and gloss retentionwithout sacrificing the desired properties of corrosion resistance andchemical resistance.

U.S. Pat. No. 4,250,074 discloses a known epoxy siloxane compositioncomprising an interpenetrating polymer network (IPN) of intertwinedepoxy polymers and polysiloxane polymers. The composition is prepared bysimultaneously polymerizing, at substantially balanced reaction rates, amixture of epoxy resin and silane groups to form two intertwinednetworks of polymerized epoxy and polysiloxane throughout a resultingcoating. An amine curing agent is used to form the polymerized epoxynetwork, and water is distributed throughout the mixture to causehydrolytic polycondensation of silane groups to form the polysiloxane.While this epoxy siloxane coating composition displayed improvedproperties of weatherability, corrosion and chemical resistance whencompared to conventional nonsiloxane-containing epoxy resincompositions, it is known to be somewhat brittle, lacking a desireddegree of impact resistance, flexibility and abrasion resistance forcertain applications.

U.S. Pat. No. 5,618,860 discloses a known epoxy polysiloxane compositionfor use as a coating. The composition is prepared by combining anon-aromatic epoxy resin with a difunctional aminosilane hardener, anorganotin catalyst, and an optional pigment. The so-formed epoxypolysiloxane composition provided improved properties of weatherability,chemical and corrosion resistance, and impact resistance when comparedto conventional nonsiloxane-containing epoxy resin compositions. Whilethis epoxy siloxane coating composition provided such improvedperformance properties, like the epoxy siloxane composition discussedabove, it too is known to be somewhat brittle, lacking a desired degreeof impact resistance, flexibility and abrasion resistance for certainapplications.

It is, therefore, desired that an epoxy siloxane composition bedeveloped that is both capable of providing the desired properties ofweatherability, corrosion and chemical resistance already associatedwith epoxy siloxane compositions, while also providing improvedproperties of impact resistance, flexibility and abrasion resistance. Itis desired that epoxy siloxane compositions of this invention provideimproved resistance to cracking and delamination when applied in theform of coatings.

SUMMARY OF THE INVENTION

An elastomer-modified epoxy siloxane composition is prepared, accordingto principles of this invention, by combining in the presence of water:(1) a silicone intermediate preferably in the form of an alkoxy orsilanol-functional polysiloxane; with (2) an epoxy resin preferablyhaving more than one 1,2-epoxide groups per molecule, and an epoxideequivalent weight in the range of from 100 to about 5,000; (3) anelastomeric resinous intermediate having a functionality selected fromthe group consisting of hydroxyl, isocyanate, carboxyl, epoxy,mercaptan, and amine, and being selected from the group of resinsconsisting of butenes, polybutenes, butadienes, polybutadienes,nitrites, acrylonitiriles, polysulfides, and combinations thereof; and(4) a polyfunctional amine curative agent. An optional organometalliccatalyst can be used to facilitate cure at ambient temperatureconditions.

The elastomer-modified epoxy siloxane composition may comprise in therange of from about 1 to 40 percent by weight silicone intermediate, 1to 15 percent by weight polyfunctional amine, 5 to 60 percent by weightepoxy resin, and 1 to 25 percent by weight elastomeric resinousintermediate.

These above-identified ingredients undergo hydrolysis andpolycondensation reactions when combined in the presence of water toform elastomer-modified epoxy polymers or elastomer-modifiedpolysiloxane polymers, depending on the choice of elastomeric resinousintermediate, that copolymerize with polysiloxane polymers and/or epoxypolymers to form a fully-cured elastomer-modified epoxy siloxane polymercomposition. Ultimately, the chemical and physical properties of theelastomer-modified epoxy siloxane compositions of the present inventionare affected by judicious choice of epoxy resin, silicone intermediate,polyfunctional amine hardener, and pigment. Elastomer-modified epoxysiloxane compositions of this invention are unique, when compared toconventional epoxy polysiloxane compositions, in that the incorporatedelastomer serves to provide an improved degree of flexibility, impactresistance, crack resistance, and abrasion resistance to finally-curedcoatings formed therefrom. These improved properties are providedwithout detracting from the desired properties of weatherability,chemical and corrosion resistance.

DETAILED DESCRIPTION OF THE INVENTION

Elastomer-modified epoxy siloxane compositions of this invention areprepared, according to one example, by reacting an epoxy-containingingredient with a polyamine or aminosilane ingredient to form a curedepoxysilane polymer, and reacting the aminosilane ingredient with asilicone intermediate to form a polysiloxane polymer. Epoxy siloxanecompositions of this invention are referred to as being“elastomer-modified” due to the additional reaction of an elastomericresin with the epoxy-containing ingredient, the silicone intermediate,or the aminosilane or polyamine depending on the type of elastomericresin functionality. Elastomer-modified epoxy siloxane compositions ofthis invention provide improved properties of impact resistance,flexibility, and abrasion resistance when compared to conventionalnonelastomer-modified epoxy siloxane compositions.

Elastomer-modifier epoxy siloxane compositions are prepared, accordingto principles of this invention, by combining in the presence of water;

-   -   (a) an aromatic or nonaromatic epoxy resin having at least two        1,2-epoxide groups; with    -   (b) an alkoxy or silanol-functional silicone intermediate;    -   (c) a polyfunctional amine;    -   (d) a reactive elastomeric resinous intermediate; and    -   (e) an optional organometallic catalyst

Elastomer-modified epoxy siloxane compositions of this invention mayalso contain other components such as optional pigments and/or solvents,Theological modifiers, plasticizers, thixotropic agents, antifoam agentsand solvents and the like to achieve the desired properties sought bythe user.

With respect to the epoxy resin ingredient, useful epoxy resins includemore than one 1,2-epoxy group per mole and may be saturated orunsaturated, aliphatic, cycloaliphatic, or heterocyclic. The epoxideresins generally contain glycidyl ester or glycidyl ether groups, have aweight per epoxide (i.e., an epoxide equivalent weight) of from 100 to5,000, and have a reactivity of about two. The epoxy resin is preferablyprovided in liquid rather than solid form.

Example epoxy resins useful for forming compositions of this inventioninclude glycidyl polyethers of polyhydric phenols which are derived froman epihalohydrin, e.g., epichlorohydrin, and a polyhdric phenol.Examples of such polyhydric phenols include resorcinol, hydroquinone,bis(4-hydroxyphenyl)-2,2-propane, or bisphenol A as it is commonlycalled, 4,4′-dihydroxybenzophenone, bis(4-hydroxyphenyl)-1,1-ethane,bis(4-hydroxyphenyl)-1,1-isobutane, bis(4-hydroxy-phenyl)-2,2-butane,bis(2-dihydroxynaphthyl)methane, phloroglucinol, bis(4-hydroxyphenyl)sulfone. Additional polyhydric phenols are novolac resins containingmore than two phenol, or substituted phenol, moieties linked throughmethylene bridges as well as halogenated, e.g., brominated andchlorinated phenolic compounds.

Additional useful epoxy resins include glycidyl polyethers of polyhydricalcohols prepared by reacting a polyhydric alcohol with an epihalohydrinusing an acidic catalyst, e.g., boron trifluoride, and subsequentlytreating the resulting product with an alkaline dehydrohalogenatingagent. Included among the polyhydric alcohols that can be used in thepreparation of these polyepoxides are glycerine, ethylene glycol,propylene glycol, diethylene glycol, hexanediol, hexanetriol,trimethylol propane, trimethylol ethane, pentaerythritol and the like.

Epoxy resins and their preparations are described in U.S. Pat. Nos.2,467,171, 2,615,007, 2,615,008, 2,801,227, 2,538,072 and 3,033,803,which are herein incorporated by reference.

Still other example epoxy resins include glycidyl esters ofpolycarboxylic acids which are derived from an epihalohydrin and apolycarboxylic acid using procedures described in U.S. Pat. Nos.3,859,314 and 3,576,827, which are herein incorporated by reference.Examples of polycarboxylic acids include phthalic acid or its anhydride,isophthalic acid, terephthalic acid, tetrahydrophthalic acid,hexahydrophthalic anhydride, adipic acid, dimeriezed fatty acids,dibasic acids made from an unsaturated fatty acid and acrylic acid andthe like.

Epoxy resins useful for forming for weather resistant coatingcompositions include Epirez 505 from Rhone-Poulenc located inLousiville, Ky.; Epon DPL-862, Eponex 1510 and Eponex 1513 (hydrogenatedbisphenol A-epichlorohydrin epoxy resin) from Resolution PerformanceProducts in Houston, Tex.; Santolink LSE-120 from Monsanto located inSpringfield, Mass.; Epodil 757 (cyclohexane dimethanol diglycidylether)from Air Products and Chemicals located in Allentown, Pa.; AralditeXUGY358 and PY327 from Vantico located in Hawthorne, N.Y.; Aroflint 393and 607 from Reichold located in Durham, N.C.; and ERL4221 from UnionCarbide located in Tarrytown, N.Y.

Epoxy resins useful for forming chemical resistant coatings includeblends of Resolution Epon 828 (bisphenol A-epichlorohydrin epoxy resin)with difunctional epoxide reactive diluents such as neopentylglycoldiglycidylether, resorcinol diglycidylether and cyclohexanedimethanoldiglycidylether, bisphenol F epoxy resins i.e., Resolution Epon DPL 862(bisphenol F-epiclorohydrin epoxy resin) and epoxy phenol novalac resinssuch as: Epalloy 8250 (epoxy novalac resin) from CVC located in CherryHill, N.J.; Araldite EPN 1139 from Vantigo; and DEN432 and DEN438 fromDow Chemical.

Preferred epoxy resins include epichlorohydrin-bisphenol A epoxy resins,epochlorohydrin bisphenol F epoxy resins, hydrogenated bisphenol Aepichlorohydrin epoxy resins, glycidyl methacrylate resins, glycidylesters, phenol novolac epoxy resins and resorcinol-modified epoxy resinswhich have at least two epoxy groups in a molecule. These epoxy resinsare preferred because they enable formation of a three-dimensionalcross-linked network by reaction with an amino-functional compound orcompounds as described in better detail later.

Preferred epoxy resins useful for providing chemically resistantcompositions include those that are the combination of standardepichlorohydrin-bisphenol A epoxy resin with phenol novolac epoxy resin.Preferred epoxy resins useful for providing good weatherability, glossretention, and color retention include hydrogenated bisphenol Aepichlorohydrin resins and glycidy methacrylate-based acrylic resins.

In the range of from 5 to 60 percent by weight of the epoxy resiningredient, based on the total weight of the composition, is used toprepare elastomer-modified epoxy siloxane compositions of thisinvention. It is to be understood that this amount reflects the totalamount of epoxy resin ingredients that are used to prepare thecomposition, which can comprise a single epoxy resin ingredient or acombination of two or more different epoxy resin ingredients.

Using less than about 5 percent by weight of the epoxy resin willproduce a final composition having an undesired degree of chemicalresistance and/or weatherability for many coating applications. Usinggreater than about 60 percent by weight epoxy resin will produce a finalcomposition having an undesired degree of flexibility, impactresistance, and abrasion resistance due to the limited amount of theelastomeric ingredient. A preferred weight percent range for the epoxyresin ingredient is between 10 and 30. A particularly preferredelastomer-modified epoxy siloxane composition is prepared by usingapproximately 20 percent by weight of the epoxy ingredient, based on thetotal weight of the composition.

With respect to the silicone intermediate used to make up the resincomponent, preferred silicone intermediates include, but are not limitedto, those having the following formula:

where each R₁ is selected from the group consisting of the hydroxygroup, oxygen, and alkyl, aryl, and alkoxy groups having up to sixcarbon atoms. Each R₂ is selected from the group consisting of hydrogenand alkyl and aryl groups having up to six carbon atoms. It is preferredthat R₁ and R₂ comprise groups having less than six carbon atoms tofacilitate rapid hydrolysis of the silicone intermediate, which reactionis driven by the volatility of the alcohol analog product of thehydrolysis. R₁ and R₂ groups having greater than six carbon atoms tendto impair the hydrolysis of the silicone intermediate due to therelatively low volatility of each alcohol analog.

It is preferred that the “n”, or number of repeating Si—O groups in themolecule backbone, be selected so that the silicone intermediateingredient have a weight-average molecular weight in the range of fromabout 400 to about 10,000. A silicone intermediate ingredient having aweight-average molecular weight of less than about 400 can produce acomposition that is too brittle for practical coating applications. Asilicone intermediate ingredient having a weight-average molecularweight of greater than about 10,000 can produce a composition having aviscosity outside a desired range of from about 1,000 to 15,000centipoise (cP) at 20° C., making the composition too viscous forapplication without adding solvent in excess of current volatile organiccontent (VOC) requirements.

Preferred silicone intermediate ingredients are alkoxy orsilanol-functional. Particularly preferred alkoxy-functional siliconeintermediates are methoxy-functional polysiloxanes and include, but arenot limited to: DC-3074 and DC-3037 from Dow Corning; GE SR191, SY-550,and SY-231 from Wacker located in Adrian, Mich. Preferredsilanol-functional silicone intermediates include, but are not limitedto, Dow Corning's DC840, Z6018, Q1-2530 and 6-2230.

In the range of from 1 to 40 percent by weight of the siliconeintermediate ingredient, based on the total weight of the composition,is used to prepare elastomer-modified epoxy siloxane compositions ofthis invention. It is to be understood that this amount reflects thetotal amount of silicone intermediate ingredients that are used toprepare the composition, which can comprise a single siliconeintermediate ingredient or a combination of two or more differentsilicone intermediate ingredients. Using less than about 1 percent byweight of the silicone intermediate will produce a final compositionhaving an undesired degree of chemical resistance and/or weatherabilityfor many coating applications. Using greater than about 40 percent byweight silicone intermediate will produce a final composition having anundesired degree of brittleness, i.e., low impact resistance, in thecured film.

A preferred weight percent range for the silicone intermediateingredient is between 2 and 20. A particularly preferredelastomer-modified epoxy siloxane composition is prepared by usingapproximately 5 percent by weight of the silicone intermediateingredient, based on the total weight of the composition.

With respect to the polyfunctional amine ingredient, usefulpolyfunctional amine ingredients for forming elastomer-modified epoxysiloxane compositions of this invention include aminofunctional siliconecompounds and amine functional compounds, and can be selected from thegeneral classes of aliphatic amines and polyamines, aliphatic amineadducts, polyamidoamines, cycloaliphatic amines and polyamines, andcycloaliphatic amine adducts, aromatic amines, Mannich bases, ketimines,and amine-functional butadiene acrylonitrile such as ATBN available fromNoveon.

A preferred amine ingredient is an aminosilane that is at leastdifunctional, i.e., having at least two active hydrogens, and which mayhave the following general formula:Y—Si—(O—X)₃where Y is H(HNR)_(a), and where “a” is an integer of from 1 to 6, eachR is a difunctional organic radical independently selected from thegroup consisting of aryl, alkyl, dialkylaryl, alkoxyalkyl, andcycloalkyl radicals, and where R can vary within each Y molecule. Each Xcan be the same or different, and is limited to alkyl, hydroxyalkyl,alkoxyalkyl and hydroxyalkoxyalkyl groups containing less than about sixcarbon atoms. At least 0.7 equivalents of amine or 0.2 moles ofaminosilane per equivalent of epoxy may be present in the amineingredient. The aminosilane can be replaced in whole or in part with anorganic amine curative.

Preferred aminosilanes include, but are not limited to: aminoethylaminopropyl triethoxysilane, n-phenylaminopropyl trimethoxysilane,trimethoxysilylpropyl diethylene triamine, 3-(3-aminophenoxy)propyltrimethoxy silane, amino ethyl amino methyl phenyl trimethoxy silane, 2amino ethyl 3 aminopropyl, tris 2 ethyl hexoxysilane, n-aminohexylaminopropyl trimethoxysilane, trisaminopropyl trismethoxy ethoxy silane,gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane,gamma-aminopropymethyldimethoxysilane,N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane,N-beta-(aminoethyl)-gamma-aminopropyltriethoxysilane, andN-beta-(aminoethyl)-gamma-aminopropymethyldimethoxysilane. Theseamino-functional compounds can be used alone or in combination with oneor more other amino-functional compounds

The manufacturers and trade names of some aminosilanes useful in thepresent invention are listed in Table 1

TABLE 1 Aminosilanes Manufacturer Product Designation Dow Corning Z6020,XI-6100, XI6150 OSI Specialities A1100, A1101, A1102, A1108, A1110,A1120 A1126, A1130, A1387, Y9632 Wacker ED117 Sivento A0696, A0698,A0699, A0700, A0710, A0720, A0733, A0733, A0742, A0750, A0800 PCR12328-1

Preferred amine ingredients are at least difunctional silanes. Aparticularly preferred difunctional silane isN-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane. Difunctionalaminosilanes are desired because it has been found that the combinationof an aminosilane having a reactivity of two, i.e., having only twoamine hydrogens, reacts with the non-aromatic epoxy, also having areactivity of two, to form a linear noncross-linked epoxy polymer thatdisplays improved weatherability. Use of the aminosilane ingredient isdesired to provide the property of chemical resistance, to acids such assulfuric acid and acetic acid, to the finally-cured coating.

Such preferred amines and aminosilanes produce elastomer-modified epoxysiloxane compositions that, when applied as a substrate coating, exhibitsuperior weatherability in terms of both color and gloss retention. Inthe range of from 1 to 25 percent by weight of the amine ingredient,based on the total weight of the composition, is used to prepareelastomer-modified epoxy siloxane compositions of this invention. It isto be understood that this amount reflects the total amount of amineingredients that are used to prepare the composition, which can comprisea single amine ingredient or a combination of two or more differentamine ingredients.

Using less than about 1 percent by weight of the amine ingredient willproduce a final composition having an undesired degree of chemicalresistance and/or weatherability for many coating applications. Usinggreater than about 25 percent by weight amine ingredient will produce afinal composition having an undesired degree of amine blush. Theformation of blush (sometimes called blooming or exodate) usually has adetrimental effect on coating performance because it can lead to glossreduction, increased yellowing, poor recoatability, and intercoatadhesion problems. Using more than 25 percent by weight amine ingredientcan also promote carbamate formation and water spotting from regions ofamine, carbon dioxide and water at the coating surface. A preferredweight percent range for the amine ingredient is between 2 and 20. Aparticularly preferred elastomer-modified epoxy siloxane composition isprepared by using approximately 7 percent by weight of the amineingredient, based on the total weight of the composition.

In preparing elastomer-modified epoxy-siloxane compositions of thepresent invention, the proportion of amine ingredient to the epoxy resincan vary over a wide range, regardless of whether the amine is chosenfrom the general classes of polyfunctional amines, or frompolyfunctional aminosilanes of the general formula above, or anycombination thereof. In general, the epoxy resin component is cured withsufficient amine ingredient to provide at least from about 0.7 to about1.2 amine equivalent weight per 1 epoxide equivalent weight, or with atleast 0.2 moles of aminosilane per epoxide equivalent weight. If theamount of amine added provides less than 0.7 amine equivalent weight perepoxide equivalent weight, the resulting coating composition producedcan exhibit a slow cure time and display inferior weatherability andchemical resistance. If the amount of amine added provides greater than1.2 amine equivalent weight per epoxide equivalent weight, the resultantcoating composition can exhibit surface blushing or greasiness.

With respect to the reactive elastomeric resinous intermediateingredient, suitable reactive elastomeric resin intermediates includethose having hydroxyl, epoxy, isocyanate, carboxyl, epoxy, mercaptan, oramine functionalities. Example reactive elastomeric resin intermediatesinclude hydroxyl-functional polybutenes; hydroxy andisocyanate-functional polybutadiene resin available, for example, fromARCO of Lyondell, Newtown Square, Pa., sold under the productdesignation Poly-BD; urethane-modified epoxy resins available, forexample, from Reichhold of Durham, N.C., sold under the productdesignation Epotuf 95-472; urethane-modified amine curatives available,for example, from Resolution Performance Products of Houston, Tex., soldunder the product designation Euredur 70; Aradur 70 available, forexample, from Vantico of Basil, Switzerland; amine andcarboxy-functional butadiene-acrylonitrile resins available, forexample, from Noveon Speciality Chemicals of Brecksville, Ohio, soldunder the product designations ATBN and CTBN; epoxy adducts of amine andcarboxy-functional butadiene-acrylonitirile resins available, forexample, from Resolution, sold under the product designations Epon58005, 58006, 58042, and 58901, from Reichhold sold under the productdesignations Kelpoxy 519-K2-70, Kelpoxy G-272, and Kelpoxy G293, andfrom CVC Specialty Chemicals of Mapleshade, N.J., sold under the productdesignations Erisys EMR-95, Erisys EMRA-1340 and Erisys EMRF-1320; andthe mercaptan and epoxy-functional polysulfide resins available, forexample, from Rohm & Haas of Philadelphia, Pa. sold under the productdesignation Thiokol LP. Other elastomeric resinous ingredients founduseful in the practice of this invention include amine-functional resinsEpi-Cure DPC-3163, Epi-Cure 3164 and Epi-Cure 3260 from ResolutionPerformance Products.

Preferred reactive elastomeric resinous intermediates include the epoxyadducts of amine and carboxy-functional butadiene-acrylonitrile resins(for example, Resolution Epon 58005 and Reichhold Kelpoxy G272). Theseparticular reactive elastomeric resinous intermediates are preferredbecause they have a sufficient elastomer content and a weight-averagemolecular weight of the adducted resin to provide optimum properties offlexibility and viscosity to the coating composition.

In the range of from 1 to 25 percent by weight of the reactiveelastomeric resinous intermediate, based on the total weight of thecomposition, is used to prepare elastomer-modified epoxy siloxanecompositions of this invention. It is to be understood that this amountreflects the total amount of reactive elastomeric resinous intermediateingredients that are used to prepare the composition, which can comprisea single reactive elastomeric resinous intermediate ingredient or acombination of two or more different reactive elastomeric resinousintermediate ingredients.

Using less than about 1 percent by weight of the reactive elastomericresinous intermediate ingredient will produce a final composition havingan undesired degree of flexibility, impact resistance, and abrasionresistance for many coating applications. Using greater than about 25percent by weight of the reactive elastomeric resinous intermediateingredient will produce a final composition that is very viscous, makingsuch coating very difficult to apply above 25 percent.

A preferred weight percent range for the reactive elastomeric resinousintermediate ingredient is between 2 and 20. A particularly preferredelastomer-modified epoxy siloxane composition is prepared by usingapproximately 4 percent by weight of the reactive elastomeric resinousintermediate ingredient, based on the total weight of the composition.

Elastomer-modified epoxy siloxane compositions of this invention areformulated for application with conventional air, airless, air-assistedairless and electrostatic spray equipment, brush, or roller. Thecompositions are intended to be used as protective coatings for steel,galvanizing, aluminum, concrete and other substrates at dry filmthicknesses in the range of from 25 micrometers to about twomillimeters, and can be applied as protective floorings for conventionfloor surfaces at dry film thicknesses in the range of from about 15 to200 millimeters.

Pigments and/or fillers can be used if desired to provide colored ortextured coating compositions. Useful color pigments may be selectedfrom organic and inorganic color pigments which may include titaniumdioxide, carbon black, lampblack, zinc oxide, natural and synthetic red,yellow, brown and black iron oxides, toluidine and benzidine yellow,phthalocyanine blue and green, and carbazole violet, and extenderpigments including ground and crystalline silica, barium sulfate,magnesium silicate, calcium silicate, mica, micaceous iron oxide,calcium carbonate, zinc powder, aluminum and aluminum silicate, gypsum,feldspar and the like. Useful fillers include conventional fillers knownin the coatings industry such as silica powder, talc (magnesiumsilicate), clays such as china clay (aluminum silicate), wollastonite(calcium silicate), calcium carbonate, barites (barium sulfate), bariummetaborate, aluminum trihydrate, graphite, zinc, aluminum, copper andthe like.

The amount of pigment that is used to form the composition is understoodto vary, depending on the particular composition application, therequirement of hiding over the substrate or undercoat, and can be zerowhen a clear or colorless composition is desired. In an exampleembodiment where a grey colored coating is desired, a combination of twodifferent pigments, e.g., lampblack and titanium dioxide can be used. Anexample elastomer-modified epoxy siloxane composition may comprise up toabout 70 percent by weight pigment and/or filler, based on the totalweight of the composition. Using greater than 70 percent by weightpigment and/or filler can produce a composition that is too viscous forapplication.

The pigment and/or filler can be added as part of the resin componentsused to form the composition, e.g., with the epoxy resin, siliconeintermediate, and reactive elastomer resinous intermediate, and/or canbe added as a separate powder component. The pigment and/or filler, whenadded as part of the resin component, is dispersed with a Cowles mixerto at least 3 Hegman fineness of grind, or alternatively is ball milledor sand milled to the same fineness of grind. Selection of a fineparticle size pigment and/or filler, and dispersion or milling to about3 Hegman grind, allows for the atomization of mixed resin and curecomponents for application by conventional air, air-assisted airless,airless and electrostatic spray equipment, and provides a smooth,uniform surface appearance after application.

Water is an important ingredient of the present invention and should bepresent in an amount sufficient to bring about both the hydrolysis ofthe silicone intermediate and the subsequent condensation of the silanolgroups. The sources of water are mainly atmospheric humidity andadsorbed moisture on the pigment material. Additional “free” water maybe added to accelerate cure depending on ambient conditions, such as theuse of the coating and flooring composition in arid environments. Apreferred elastomer-modified epoxy siloxane composition comprises up toa stoichiometric amount of water to facilitate hydrolysis. Compositionsthat are prepared without added water may not contain the amount ofmoisture needed for the hydrolysis and condensation reactions, and maytherefore produce a composition product having an insufficient degree ofultraviolet, corrosion and chemical resistance. Compositions that areprepared using greater than about one percent by weight water tend tohydrolyze and polymerize to form an undesirable gel before application.

If desired, water may be added to either the epoxide resin ingredient orthe polyfunctional amine ingredient. Other sources of water may includetrace amounts present in the epoxide resin ingredient, polyfunctionalamine ingredient, thinning solvent, or other ingredients. Water may alsobe incorporated by using ketimines or alcohol-solvent-water mixtures asdescribed in U.S. Pat. No. 4,250,074, which is incorporated herein byreference.

Regardless of its source, the total amount of water that is used shouldbe the stoichiometric amount needed to facilitate the hydrolysisreaction. Water exceeding the stoichiometric amount is undesirable sinceexcess water acts to reduce the surface gloss of the finally-curedcomposition product. Since coating compositions of this invention can beapplied, for flooring application, in thickness from about 15 to about200 millimeters, it is important to add a sufficient amount of water anddistribute the same uniformly in the combined material to ensure properdrying and curing for the higher thickness applications. A particularlypreferred elastomer-modified epoxy siloxane composition is prepared byusing less than about 0.1 percent by weight water.

With respect to the optional organometallic catalyst, suitableorganometallic catalysts useful for forming elastomer-modified epoxysiloxane compositions of this invention include the metal driers wellknown in the paint industry, e.g. zinc, manganese, zirconium, titanium,cobalt, iron, lead and tin each in the form of octoates, neodecanatesand naphthanates. Suitable catalysts include organotin catalysts havingthe general formula

where R5 and R6 are each selected from the group consisting of alkyl,aryl, and alkoxy ester groups having up to eleven carbon atoms, andwhere R7 and R8 are each selected from the same groups as R5 and R6, orfrom the group consisting of inorganic atoms such as halogens, sulphuror oxygen. Dibutyl tin dilaurate, dibutyl tin diacetate, dibutyl tindiacetyl acetonate, dibutyl tin diethyl hexaoate, organotitanates,sodium acetate, and aliphatic secondary or tertiary polyamines includingpropylamine, ethylamino ethanol, triethanolamine, triethylamine, andmethyl diethanol amine may be used alone or in combination to acceleratehydrolytic polycondensation of silicone intermediate and silane. Apreferred catalyst is dibutyl tin dilaurate.

Up to about five percent by weight of the organometallic catalyst, basedon the total weight of the composition, is used to speed drying andcuring of the elastomer-modified epoxy siloxane compositions of thisinvention. The organometallic catalyst can be added to the resincomponent, or may be added as an entirely separate component. It is tobe understood that this amount reflects the total amount oforganometallic catalyst ingredients that are used to prepare thecomposition, which can comprise a single organometallic catalystingredient or a combination of two or more different organometalliccatalyst ingredients. Using greater than about five percent by weight ofthe organometallic catalyst ingredient will produce a final compositionhaving a pot life or working time that may be to short for practicaluse.

Elastomer-modified epoxy siloxane compositions of the present inventionare generally low in viscosity and can be spray applied without theaddition of a solvent. However, organic solvents may be added to improveatomization and application with electrostatic spray equipment or toimprove flow, leveling, and/or appearance when applied by brush, roller,or standard air and airless spray equipment. Exemplary solvents usefulfor this purpose include esters, ethers, alcohols, ketones, glycols andthe like. The maximum amount of solvent added to compositions of thepresent invention is limited by government regulation under the CleanAir Act to approximately 420 grams solvent per liter of the composition.

Elastomer-modified epoxy siloxane compositions of the present inventionmay also contain rheological modifiers, plasticizers, antifoam agents,flow control agents, slip and mar agents, thixotropic agents, pigmentwetting agents, bituminous and asphaltic extenders, antisettling agents,diluents, UV light stabilizers, air release agents and dispersing aids.A preferred elastomer-modified epoxy siloxane composition may compriseup to about ten percent by weight such modifiers and agents.

Elastomer-modified epoxy siloxane compositions of the present inventioncan be supplied as a two-package system in moisture proof containers,wherein one package contains the resin components, i.e., the epoxyresin, silicone intermediate, and reactive elastomeric resinousintermediate, and any pigment and/or filler, additives and solvent ifdesired. A second package contains the polyfunctional amine ingredientand any optional catalysts or accelerating agents. Alternatively,compositions of this invention can be supplied as a three-packagesystem, wherein a first package contains the resin components, a secondpackage contains the polyfunctional amine ingredient, and a thirdpackage contains the powder components, e.g., the pigments and/orfillers.

Elastomer-modified epoxy siloxane compositions of the present inventioncan be applied and fully cure at ambient temperature conditions in therange of from about −6° C. to 50° C. At temperatures below −18° C. cureis severely retarded. However, compositions of the present invention maybe applied under bake or cure temperatures up to 150° C. to 200° C.

While not wishing to be bound by any particular theory or mechanism, itis believed that elastomer-modified epoxy siloxane compositions of thepresent invention are formed by the following reactions. The epoxy resiningredient reacts the amine moiety of the polyfunctional amine oraminosilane ingredient and undergoes an epoxy-amine addition reaction toform a three-dimensional cross linked network.

In the event that the silicone intermediate is alkoxy-functional, it isbelieved to undergo a hydrolysis reaction in the presence of water toform a silanol-functional silicone intermediate. The silanol-functionalsilicone intermediate then undergoes hydrolytic polycondensation toproduce alcohol and polysiloxane polymers.

The reactive elastomeric resinous intermediate is believed to react inthe following manner. If the elastomeric resinous ingredient is hydroxyor carbonyl-functional, it reacts with the silanol groups of thesilicone intermediate and forms part of the polysiloxane polymer. If theelastomeric resinous ingredient is epoxy-functional, it reacts with thepolyfunctional amine or aminosilane ingredient and forms part of theepoxy-silane polymer. If the elastomeric resinous ingredient ismercaptan or amine-functional, it reacts with the epoxy resin ingredientand forms part of the epoxy-silane polymer.

The so formed elastomer-modified epoxy polymer or elastomer-modifiedpolysiloxane polymer copolymerize, i.e., the silane moiety of theaminosilane undergoes hydrolytic polycondensation with the polysiloxane,with the other of the polysiloxane polymer or epoxy polymer to form afully-cured elastomer-modified epoxy siloxane polymer composition. Inits cured form, the elastomer-modified epoxy siloxane polymercomposition exists as a uniformly dispersed arrangement of linear epoxychain fragments that are cross-linked with a continuous polysiloxanepolymer chain, thereby forming a non-interpenetrating elastomer-modifiedpolymer network (IPN) chemical structure that has substantial advantagesover conventional epoxy polysiloxane systems.

When the ingredients are combined, it is believed that the silane moietyof the aminosilane ingredient condenses with the silicone intermediateingredient, and the epoxy resin undergoes chain extension with byreaction with the amino groups pendent from the silicone intermediatepolysiloxane to form a fully-cured elastomer-modified epoxy siloxanecomposition. As discussed above, either the polysiloxane polymer orepoxy-silane polymer may be elastomer modified depending on theparticular type of elastomer functionality. In such reaction it isbelieved that the epoxy resin functions as a cross-linking enhancer thatadds to the cross-link density of the composition without diminishingthe beneficial features of the polysiloxane.

Ultimately, the chemical and physical properties of theelastomer-modified epoxy siloxane compositions of the present inventionare affected by judicious choice of epoxy resin, silicone intermediate,polyfunctional amine hardener, and pigment. Elastomer-modified epoxysiloxane compositions of this invention are unique, when compared toconventional epoxy polysiloxane compositions, in that the incorporatedelastomer serves to provide an improved degree of flexibility, crackingresistance, impact resistance and abrasion resistance to finally-curedcoatings formed therefrom. These improved properties are providedwithout detracting from the desired properties of weatherability,chemical and corrosion resistance.

Additionally, elastomer-modified epoxy siloxane compositions of thisinvention provide improved cured film properties, such as reducedshrinkage and improved resistance to cracking and delamination whencompared to conventional epoxy polysiloxane compositions. Conventionalepoxy polysiloxane compositions are highly cross linked and exhibit highshrinkage when fully cured, which shrinkage can result in cracking ordelamination of coating or flooring formulations on steel or concretesubstrates.

These and other features of the present invention will become moreapparent upon consideration of the following examples:

EXAMPLE 1

A resin component was prepared by combining approximately 10 grams epoxyphenol novalac resin (Epalloy 8250 or EPN 9850CH), 0.14 grams additive(BYKO80 defoamer), 3 grams Titanium dioxide pigment, 0.1 grams lampblackpigment, 4 grams silicone intermediate (DC-3074, SY231 alkoxy-functionalsilicone intermediate), 9 grams bisphenol A epoxy resin (DER 331), 3grams elastomer-modified resin (Kelpoxy G272-100 epoxy-terminatedelastomeric copolymer), and 0.04 grams deionized water. To the resincomponent was added a cure component in the form of approximately 7grams aminosilane (Z6020 aminosilane), and a powder component in theform of 45 grams silica, and 19 grams talc. The resin, cure, and powdercomponents were combined and mixed by hand for a period of one or twominutes.

EXAMPLE 2

A resin component was prepared by combining approximately 10 grams epoxyphenol novalac resin (Epalloy 8250 or EPN 9850CH), 0.14 grams additive(BYKO80 defoamer), 3 grams Titanium dioxide pigment, 0.1 grams lampblackpigment, 4 grams silicone intermediate(DC-3074, SY231 alkoxy-functionalsilicone intermediate), 7 grams bisphenol A epoxy resin (DER 331), 7grams elastomer-modified resin (Kelpoxy G272-100 epoxy-terminatedelastomeric copolymer), and 0.04 grams deionized water. To the resincomponent was added a cure component in the form of approximately 7grams aminosilane (Z6020 aminosilane), and a powder component in theform of 45 grams silica, and 19 grams talc. The components were combinedand mixed by hand for a period of from one or two minutes. Thecomposition was similar to that prepared according to Examiner 1, exceptthat it included a reduced amount of epoxy resin and a roughly doubledamount of the elastomer resinous intermediate ingredient.

The elastomer-modified epoxy siloxane compositions of Examples 1 and 2were prepared using cylindrical compressive strength test specimenshaving a dimension of 1″diameter by 1″high. The test specimens werecured at room temperature for 14 days and then immersed completely intosolutions of concentrated sulfuric acid, concentrated hydrochloric acid,methanol and ammonium hydroxide for 7 days. Afterwards, each testspecimen was evaluated for coating integrity and displayed satisfactorycoating integrity. Compressive strength was measured per ASTM C579before and after immersion into the above-described chemicals. All ofthe test specimens retained greater than 90 percent of their initialcompressive strength after immersion. These results are comparable orbetter than other conventional epoxy-siloxane composition known in theart.

The elastomer-modified epoxy siloxane compositions of Examples 1 and 2were also applied to the surface of concrete blocks at a film thicknessof 80 to 120 millimeters for purposes of temperature cycling. A concreteblock was also coated with a conventional epoxy polysiloxane compositionat the same coating thickness for comparative purposes. The coatedblocks were cured at ambient temperature for seven days, and exposed toa temperature of 60° C. for seven days. This temperature cycle wasrepeated until one of the coated blocks developed cracking ordelamination from the concrete. Elastomer-modified epoxy siloxanecompositions of Examples 1 and 2 demonstrated superior resistance tocracking and delamination, by showing no signs of cracking ordelamination within the same number of temperature cycles that it tookthe block coated with the conventional epoxy polysiloxane to fail bycracking and delaminating.

Although elastomer-modified epoxy siloxane compositions of the presentinvention have been described with considerable detail with reference tocertain preferred variations thereof, other variations are possible.Therefore, the spirit and scope of the appended claims should not belimited to the preferred variations described herein.

1. An elastomer-modified epoxy siloxane composition comprising: water;an alkoxy or silanol-functional silicone intermediate; an amine curativeagent selected from the group consisting of amino-functional compoundsand aminofunctional silicone compounds; an epoxy resin; and anelastomeric resinous intermediate having a functionality selected fromthe group consisting of hydroxyl, epoxy, isocyanate, carboxyl,mercaptan, and amine.
 2. The elastomer-modified epoxy siloxanecomposition as recited in claim 1 wherein the amine curative agent is anaminosilane.
 3. The elastomer-modified epoxy siloxane composition asrecited in claim 1 additionally comprising at least one organometalliccatalyst to facilitate cure at ambient temperature.
 4. Theelastomer-modified epoxy siloxane composition as recited in claim 1wherein the elastomeric resinous intermediate is selected from the groupconsisting of epoxy resins, polybutene resins, polybutadiene resins,acrylonitrile resins, polysulfide resins, and combinations thereof. 5.The elastomer-modified epoxy siloxane composition as recited in claim 1wherein the silicone intermediate has a weight-average molecular weightof from 400 to 10,000.
 6. The elastomer-modified epoxy siloxanecomposition as recited in claim 1 wherein the epoxy resin ingredient isselected from die group consisting of epichlorohydrin-bisphenol A epoxyresins, epochlorohydrin bisphenol F epoxy resins, hydrogenated bisphenolA epichlorohydrin epoxy resins, glycidyl methacrylate resins, glycidylesters, phenol novalac epoxy resins, resorcinol-modified epoxy resins,and combinations thereof.
 7. The elastomer-modified epoxy siloxanecomposition as recited in claim 1 wherein the elastomer-modified epoxysiloxane composition in its cured form exists as a uniformly dispersedarrangement of linear epoxy chain fragments that are cross-linked with acontinuous polysiloxane chain.
 8. The elastomer-modified epoxy siloxanecomposition as recited in claim 1 wherein the amine curative agent is anaminosilane that includes at least two active hydrogens, and the epoxyresin has more than one 1,2-epoxide groups per molecule.
 9. Theelastomer-modified epoxy siloxane composition as recited in claim 1comprising from about 0.7 to 1.2 amine equivalent weight per epoxideequivalent weight.
 10. An elastomer-modified epoxy siloxane compositionprepared by combining; water; a silicone intermediate selected from thegroup consisting of alkoxy and silanol-functional polysiloxanes; anaminosilane; an epoxy resin having at least two 1,2-epoxide groups; andan elastomeric resinous intermediate having a functionality selectedfrom the group consisting of hydroxyl, epoxy, isocyanate, carboxyl,mercaptan, and amine.
 11. The elastomer-modified epoxy siloxanecomposition as recited in claim 10 wherein the silicone intermediate hasthe formula

where each R₁ is selected from the group consisting of hydroxy, alkyl,aryl and alkoxy groups having up to six carbon atoms, each R₂, isselected from the group consisting of hydrogen, alkyl, and aryl groupshaving up to six carbon atoms.
 12. The elastomer-modified epoxy siloxanecomposition as recited in claim 10 wherein the epoxy resin ingredient isselected from the group consisting of epichlorohydrin-bisphenol A epoxyresins, epochlorohydrin bisphenol F epoxy resins, hydrogenated bisphenolA epichlorohydrin epoxy resins, glycidyl methacrylate resins, glycidylesters, phenol novalac epoxy resins, resorcinol-modified epoxy resins,and combinations thereof.
 13. The elastomer-modified epoxy siloxanecomposition as recited in claim 10 additionally comprising at least onemetal catalyst to facilitate cure at ambient temperature, wherein thecatalyst is selected from the group consisting of zinc, manganese,zirconium, titanium, cobalt, iron, lead, and tin each in the form ofoctonates, neodecanates, or naphthanates.
 14. The elastomer-modifiedepoxy siloxane composition as recited in claim 10 comprising in therange of from about 1 to 40 percent by weight silicone intermediate, 1to 15 percent by weight aminosilane, 5 to 60 percent by weight epoxyresin, and 1 to 25 percent by weight elastomeric resinous intermediate.15. An elastomer-modified epoxy siloxane composition prepared bycombining in the presence of water: a silicone intermediate having theformula

where each R₁ is selected from the group consisting of hydroxy, alkyl,aryl and alkoxy groups having up to six carbon atoms, each R₂ isselected from the group consisting of hydrogen, alkyl, and aryl groupshaving up to six carbon atoms and, wherein n is selected so that theweight-average molecular weight for the polysiloxane is in the range offrom about 400 to 10,000; an aminosilane; an epoxy resin having anepoxide equivalent weight in the range of from 100 to about 5,000; andan elastomeric resinous intermediate having a functionality selectedfrom the group consisting of hydroxyl, epoxy, isocyanate, carboxyl,mercaptan, and amine.
 16. The elastomer-modified epoxy siloxanecomposition as recited in claim 15 additionally comprising at least oneorganometallic metal catalyst to facilitate cure at ambient temperature.17. The elastomer-modified epoxy siloxane composition as recited inclaim 15 comprising from about 0.7 to 1.2 amine equivalent weight perepoxide equivalent weight.
 18. The elastomer-modified epoxy siloxanecomposition as recited in claim 15 comprising in the range of from about1 to 40 percent by weight silicone intermediate, 1 to 15 percent byweight aminosilane, 5 to 60 percent by weight epoxy resin, and 1 to 25percent by weight elastomeric resinous intermediate.
 19. Theelastomer-modified epoxy siloxane composition as recited in claim 15wherein the elastomer-modified epoxy siloxane composition in its curedform exists as a uniformly dispersed arrangement of linear epoxy chainfragments that are cross-linked with a continuous polysiloxane chain.20. The elastomer-modified epoxy siloxane composition as recited inclaim 15 wherein the aminosilane includes at least two active hydrogens,and the epoxy resin has more than one 1,2-epoxide groups per molecule.21. An elastomer-modified epoxy siloxane composition prepared bycombining the contents of; a first container comprising an epoxy resin,an alkoxy- or silanol-functional silicone intermediate, and a reactiveelastomeric resinous intermediate having a functionality selected fromthe group consisting of hydroxyl, epoxy, isocyanate, carboxyl,mercaptan, and amine; with a second container comprising an amineingredient selected from the group consisting of amino-functionalcompounds and aminofunctional silicone compounds.